Reggie James IV had exhausted all his other options. It was time for one last-ditch effort: surgery. He was already lying on the hospital gurney. The IV was in his arm. Doctors just wanted one last double check. They asked James to lift his arm. They couldn’t believe what they felt and asked him to do it again.

His muscle had contracted. The doctor doing the examination called in another doctor and they quietly huddled on the other side of the room. After a few minutes, they broke the news to James.

“We’re not gonna have surgery,” they told him. “This is the first time we’ve seen this happen.”

Seven months ago, James’ football career looked like it was over. His best-case scenario was taking a health-imposed gap year and spending his first year after high school at home working out and waiting for his body to heal.

Instead, thanks to a medical marvel that left doctors scratching their head, he’s chasing his dream in the SEC as...